U3S multiband WSPR Beacon

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yo3fff
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Joined: 2016/04/20 - 20:04
U3S multiband WSPR Beacon

Hello,

For those of you who build the U3S Beacon from qrp-labs (and not only) and need to use it multi band, just let you know how can be done with one antenna connected.

This beacon can broadcast up to 6 bands one by one on one antenna or each band with each antenna.
I don't have 6 different antennas in place but only a long wire about 24m long.
The kind of "multi band" antenna has very different Z/band and should be tuned properly to be used with the beacon.
One can use a separate fix LC tune circuitry for each band. I did so but then the system is limited to that antenna. If later decided to move it on a another antenna then the whole LC circuits should be redesign/installed. Not so comfortable.
Then using an automatic antenna tuner can help. I have on hand a LDG L-100Plus.
All right but how this tuner can be switched to tune mode remotely by the U3S without operator?
Well, can be done by grounding the "Tune" external connector for about 600ms.
Unfortunately the U3S PTT output is "ON" for the whole transmission period and second, it is +5V active.

The solution is an Arduino with the proper software in it. I wrote the software and now everything is working.
You can check on wsprnet.org by YO3FFF on 80/40/30m just to see how it works.

I hope this will help others who want to operate a multi band beacon on a single antenna.

GL.

73 de YO3FFF
Cristi
cyo3fff@yahoo.com